auto fn1 = ( string s ) {
return s;
};
auto fn2 = ( string s ) {
return map!fn1( [""] );
};
auto idirs = map!fn2( [""] );
The above code gives the following errors:
foo.d(114): Error: struct foo.main.Map!(fn2,string[]).Map inner struct
Map cannot be a field
foo.d(114): Error: struct foo.main.Map!(fn2,string[]).Map inner struct
Map cannot be a field
As far as I can see, this has to do with struct rules, but I can't see
how to fix it. Should I file this in bugzilla?

I've had this particular error dozens of time :-( Most of the time, it
means the function you passed to (the outer) Map is not correct, be it a
template that has trouble instantiating, a type mismatch or some frame
pointer that got lost.
In your case, I guess there is a bug somewhere concerning the passing around
of delegates. If you get rid of delegates (which is not what you want, I
know), it works:
string fn1(string s) { return s;}
auto fn2(string s) { return map!fn1([""]);}
void main()
{
auto idirs = map!fn2([""]); // works.
}
I tried defining fn1 inside fn2, but it does not work. Too bad.
Philippe